Mutant of Escherichia coli with Derepressed Levels of the Biotin Biosynthetic Enzymes

A cross-feeding technique was used to isolate a mutant of Escherichia coli K-12 that excretes 1,000 times more biotin into the growth medium than the parent strain. The mutant has high levels of the biotin biosynthetic enzymes even when grown in the presence of biotin. Desthiobiotin synthetase, the level of which was used as a measure of the biosynthetic activity of the biotin pathway, is not repressed by biotin at the concentration 250,000 times that sufficient to repress the enzyme in the wild type. The mutant gene is cotransducible with argC located at 77 min on the E. coli chromosome.     

HL-A genotype of patients with acute lymphoblastic leukaemia

Summary 10 patients with acute lymphoblastic leukaemia were tissue-typed for 21 HL-A specificities. Of these, genotypes of 9 pateints were determined by family analyses. Haplotype HL-A1,8 occurred in 5 out of 18 instances. On phenotype basis, a slight increase was observed in the incidence of antigens HL-A1 and HL-A8. No loss of HL-A specificities could be detected on lymphocytes through family analyses.     

X0 Karyotype in a phenotypic male

Summary A 24-year-old male with ambiguous genitalia was found to have a predominantly 45,X chromosomal constitution. The clinical and cytological findings in this patient are presented in the report. The possible mode of origin of this aberrant phenotype due to chromosome mosaicism of 45,X/46,XY type during early embryogenesis and subsequent elimination of 46,XY cell line is discussed.     

Restriction Fragment Length Polymorphism and Random Amplified Polymorphic DNA Analysis of Chickpea Accessions

Genetic diversity analysis was carried out in chickpea accessions using restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) techniques. RFLP analysis using 26 Pst I sub-genomic clones on ten chickpea accessions in 130 probe-enzyme combinations detected polymorphism with only two clones. Pst I clones, CG 141 detected polymorphism in ICC 4918 and Pusa 209 while CG 500 detected polymorphism in Pusa 261, ILC 26 and in ILC 13326. These clones detected very few polymorphic markers. Analysis using 10 Eco RI clones on twelve chickpea accessions have shown better hybridisation signal and one clone detected polymorphism in Pusa 256. RFLP analysis of both cultivated and wild Cicer species using heterologous DNA probe Cab3C revealed polymorphism only in wild Cicer species (Cicer reticulatum L., JM 2100). RAPD analysis of 13 chickpea accessions which includes mutants of C 235 and E100Y showed greater degree of polymorphism with 1 - 5 unique DNA bands for all the accessions. Phylogenetic analysis of the RAPD data helped to group the accessions. C 235 and its mutants were found to be closely grouped while E100Y and its mutant E100Ym grouped apart. Desi and kabuli chickpea accessions however, could not be separately grouped. This revised version was published online in July 2006 with corrections to the Cover Date.     

HGF triggers activation of the COX-2 gene in rat gastric epithelial cells: action mediated through the ERK2 signaling pathway.

Although it is established that growth factors and prostaglandins function in the maintenance of gastric mucosal integrity and in the healing of gastric mucosal injury and ulceration, the regulatory relationship between growth factors and prostaglandins in the gastric mucosa is not well characterized. Therefore, we investigated whether hepatocyte growth factor (HGF) affects expression of COX-2 (the inducible form of the prostaglandin synthesizing enzyme, cyclooxygenase) in gastric epithelial cells and whether this action is mediated through the MAP (ERK) kinase signaling pathway. In RGM1 cells (an epithelial cell line derived from normal rat gastric mucosa), HGF caused an increase in COX-2 mRNA and protein by 236% and 175%, respectively (both P<0.05). This induction of COX-2 expression was abolished by pretreatment with the MAPK kinase (MEK) inhibitor PD98059. HGF also triggered a 13-fold increase in c-Met/HGF receptor phosphorylation (P<0.005) and increased ERK2 activity by 684% (P<0.01). Pretreatment with PD98059 abolished the HGF-induced increase in ERK2 activity, but not c-Met/HGF receptor phosphorylation. The specific inhibitor of p38 MAP kinase, SB203580, had no effect on HGF-induced COX-2 expression. Thus, HGF triggers activation of the COX-2 gene in gastric epithelial cells through phosphorylation of c-Met/HGF receptor and activation of the ERK2 signaling pathway.-Jones, M. K., Sasaki, E., Halter, F., Pai, R., Nakamura, T., Arakawa, T., Kuroki, T., Tarnawski, A. S. HGF triggers activation of the COX-2 gene in rat gastric epithelial cells: action mediated through the ERK2 signaling pathway.     

Effect of Phyllanthus niruri Linn. treatment on liver, kidney and testes in CCl4 induced hepatotoxic rats

Phyllanthus niruri extract is extensively used in treating liver ailments. Effects of aqueous extract of P. niruri on liver, kidney and testes of CCl4 induced hepatotoxic rats were studied. High levels of malondialdehyde (MDA) were observed in the CCl4 test group with significant reduction of MDA levels in all groups on P. niruri extract administration. Highest levels of glutathione (GSH) were found in P. niruri group. Activities of alanine transaminase, aspartate transaminase and alkaline phosphatase enzymes were significantly reduced in the curative group (P. niruri treatment after CCl4 injection). Histopathology of liver showed lesser degree of inflammation in all P. niruri treated groups while the renal and seminiferous tubules showed eosinophilic protein casts with signs of tubular damage and degeneration. Testes also showed decreased amount of mature spermatozoa. The results suggest that P. niruri has anti-oxidant and hepato-protective activity with associated deleterious effects on kidney and testes.